Method of cleaning a cylindrical water strainer utilizing reverse flow and ultrasonic energy

ABSTRACT

A method for reducing the amount of cleaned water required in cleaning a particulate strainer using a reverse flow system is disclosed herein. The method includes the steps of: disposing a stationary cylindrical strainer in a first fluid flow to capture particulates against a first upstream surface of the strainer; positioning a single self-contained ultrasonic energy source within an inner region of the stationary cylindrical strainer defined by a downstream second surface the second surface permitting passage of a cleaned fluid flow; stopping the first flow; activating the ultrasonic energy source to dislodge particulates from the first surface; sending a reverse flow of the cleaned fluid flow through the second surface and through the first surface to evacuate the dislodged particulates from returning to the first surface; and restoring the passage of the first flow through the strainer.

RELATED APPLICATIONS

This application is a divisional application of Ser. No. 09/873,526filed on Jun. 4, 2001, entitled SELF-CLEANING WATER FILTER, which inturn is a Continuation-in-Part of application Ser. No. 09/737,411 filedon Dec. 15, 2000, now U.S. Pat No. 6,517,722 which is aContinuation-in-Part of application Ser. No. 09/417,404, filed on Oct.13, 1999, now U.S. Pat. No. 6,177,022, which is a Continuation-in-Partof Co-Pending application Ser. No. 09/014,447 filed Jan. 28, 1998, nowabandoned, the latter three of which are entitled SELF-CLEANING FUEL OILSTRAINER, and all of whose entire disclosures are incorporated byreference herein.

SPECIFICATION BACKGROUND OF THE INVENTION

This invention relates generally to filter devices and, moreparticularly, to water system filters for small particulatecontaminants.

It is well-known that the mechanical cleaning of a filter surface can beaccomplished by having a brush or scraper drag along the filter surfacewhere deposits have accumulated. In certain configurations, the brush orscraper is mounted at one end between two walls but with a significantportion of the brush or scraper projecting beyond the walls. Suchconfigurations are shown in U.S. Pat. No. 148,557 (Gillespie et al.);U.S. Pat. No. 556,725 (Farwell); U.S. Pat. No. 740,574 (Kohlmeyer) andU.S. Pat. No. 793,720 (Godbe). In conventional filter systems, theparticulate contaminants are driven off the filter surface and aredeposited in a hopper or tank along with the fluid being filtered, thusdiscarding large amounts of the fluid being filtered.

The use of a brush, or high speed cleaning spray, disposed between apair of walls for cleaning a cylindrical filter is known in the art, asis disclosed in U.S. Pat. No. 5,423,977 (Aoki et al.) and U.S. Pat. No.5,595,655 (Steiner et al.) and Swiss Patent No. 22,863 (Zingg). Anothervariation employs a backwash that drives the particulate contaminantsoff of the cylindrical filter, as is disclosed in U.S. Pat. No.3,338,416 (Barry).

An exemplary use of such filters is in a water desalination system thatis available on ships. Shipboard water/salt water straining is aspecialized straining process. In particular, the water/salt water flowis initially pre-strained for gross particulate contaminants, such thatany particulate contaminants remaining in the water/salt water flow areextremely small (e.g., <100 microns, with a large percentage being lessthan 25 microns). As a result, where these small particulatecontaminants are captured by a downstream strainer (e.g., a wedge wirescreen strainer), both on and within the strainer surface, and thenlater dislodged during the strainer cleaning process, these extremelysmall particulate contaminants do not fall by gravity toward a drain butremain suspended in the water/salt water and will re-attach to thestrainer surface. Therefore, there remains a need for a cleaning devicethat can dislodge such extremely small particulate contaminants off ofthe downstream strainer surface, as well as from within the strainersurface, and then ensure that these particulate contaminants flow outthrough the drain rather than re-attaching to the strainer surface.

Thus, there is a need for an improved system for removing undesiredparticulate contaminants from a water/salt water flow and withoutinterrupting that water/salt water flow to the engines, while minimizingthe amount of fluid removed therewith. It is to just such a system thatthe present invention is directed.

SUMMARY OF THE INVENTION

A water cleaning system is disposed within a water flow havingparticulate contaminants therein. As mentioned earlier, the particulatecontaminants that need to be removed from the water flow are extremelysmall, less than 100 microns, and a large percentage of these less than25 microns, therefore do not settle out by gravity. The invention of thepresent application is well-suited to removing these small particulatecontaminants from the water flow and into a drain.

In particular, a water filter is disposed within a water flow havingparticulate contaminants therein. The water filter comprises: a porousmember in fluid communication with the water flow such that the waterflow enters the porous member through a first porous member surface andexits through a second porous member surface and wherein the water flowdeposits the particulate contaminants on the first porous membersurface; particulate-removing means disposed to be in close proximitywith the porous member for removing particulate contaminants from thefirst porous member surface along substantially the entirety of thelength of the first porous member surface; a pair of flow confiningwalls are disposed to be in close proximity with the first porous membersurface along substantially the entirety of the length of the firstporous member surface for defining a chamber; a partition divides thechamber into a first subchamber and a second subchamber along the lengthof the chamber; a drive mechanism is provided for displacing the porousmember for continuously directing particulate contaminants deposited onthe first porous surface past the particulate removing means forcontinuously dislodging the particulate contaminants from the firstporous member surface into the first subchamber; the partition includesfirst and second portions on opposite sides of the particulate removingmeans and each portion has a plurality of apertures for passing thedislodged particulate contaminants from the first subchamber into thesecond subchamber; and a drain is in communication with the secondsubchamber and through which the dislodged particulate contaminants areremoved when the drain is opened.

A method is provided for cleaning a water flow having particulatecontaminants therein. The method comprises the steps of: disposing aporous member in fluid communication with the water flow such that thewater flow enters the porous member through a first porous membersurface and exits through a second porous member surface so that thewater flow deposits the particulate contaminants on the first porousmember surface; positioning a pair of flow confining walls adjacent thefirst porous member surface to define a chamber and positioning arespective flexible member between a respective flow confining wall andthe first porous surface member, and wherein the respective flexiblemembers are in contact with the first porous surface; positioning aparticulate-removing means closely-adjacent the porous member; dividingthe chamber into first and second subchambers with a partition havingfirst and second portions on opposite sides of the particulate removingmeans and each portion having a plurality of apertures to provide fluidcommunication between the first and second subchambers and wherein thesecond subchamber is in fluid communication with a drain when the drainis opened; displacing the porous member to permit theparticulate-removing means to dislodge particulate contaminants trappedon the first porous member surface into the first subchamber; andopening the drain to cause the dislodged particulate contaminants topass through the plurality of apertures into the second subchamber andout into the drain.

A water cleaning system is provided for use with a water flow havingparticulate contaminants therein. The cleaning system comprises: aninlet valve for controlling the water flow having particulatecontaminants therein forming a contaminated water flow and wherein thecontaminated water flow flows through a first output port of the inletvalve; a stationary porous member positioned in the contaminated waterflow that passes through the first output port and wherein thecontaminated water flow enters the stationary porous member through afirst porous member surface and exits through a second porous membersurface towards a second output port, and wherein the contaminated waterflow deposits the particulate contaminants on the first porous membersurface to form a clean water flow that flows toward the second outputport; an outlet valve coupled to the second output port for controllingthe clean water flow; a flow control means, operated during a porousmember cleaning process, having a flow control means input coupled to asource of water and a flow control means output coupled to the secondoutput port and wherein the flow control means controls a reverse flowof the clean water that flows from the second porous member surfacethrough the first porous member surface for dislodging the particulatecontaminants from the first porous member surface to form a contaminatedreverse flow of water; a drain valve coupled to the first output portfor directing the contaminated reverse flow of water towards a drainduring the cleaning process; and the inlet valve and outlet valve areclosed during the cleaning process.

A method is provided for cleaning a contaminated water flow havingparticulate contaminants therein. The method comprises the steps of:positioning a stationary porous member in the contaminated water flowsuch that the contaminated water flow enters the stationary porousmember through a first porous member surface and exits through a secondporous member surface toward an output port, and wherein thecontaminated water flow deposits the particulate contaminants on thefirst porous member surface; isolating the stationary porous member fromthe contaminated water flow during a cleaning process; passing a reverseflow of clean water from the output port and through the stationaryporous member from the second porous surface member surface to the firstporous member surface for dislodging the particulate contaminants fromthe first porous member surface to form a contaminated reverse flow ofwater; opening a drain to receive the contaminated reverse flow ofwater; discontinuing the reverse flow of clean water While closing thedrain to complete the cleaning process; and recoupling the stationaryporous member to the contaminated water flow.

A water filter system for use with a water flow having particulatecontaminants therein. The water filter system comprises: an inlet valvefor controlling the water flow having particulate contaminants thereinforming a contaminated water flow and wherein the contaminated waterflows through a first output port of the inlet valve; a stationaryporous member positioned in the contaminated water flow that passesthrough the first output port, and wherein the contaminated water flowenters the stationary porous member through a first porous membersurface and exiting through a second porous member surface towards asecond output port, and wherein the water flow deposits the particulatecontaminants on the first porous member surface to form a clean waterflow that flows towards the second output port; a third output portcoupled to a drain through a drain valve; the inlet valve being closedwhile the drain valve is opened during a cleaning process for generatinga reverse flow of the water that flows from the second output porttowards the third output port, wherein the reverse flow of the cleanwater flows through the stationary porous member from the second porousmember surface through the first porous member surface for dislodgingthe particulate contaminants from the first porous member surface toform a contaminated reverse flow of water that flows into the drain; andthe drain valve being closed and the inlet valve being opened after thecleaning process is completed.

DESCRIPTION OF THE DRAWINGS

Many of the intended advantages of this invention will be readilyappreciated when the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings wherein:

FIG. 1 is a block diagram of the water-desalination system in which thepresent invention is located;

FIG. 2 is a top view of the present invention;

FIG. 3 is a partial side view of the present invention;

FIG. 4 is a bottom view of the present invention;

FIG. 5 is a cross-sectional view of the present invention taken alongline 5—5 of FIG. 2;

FIG. 6 is partial sectional view taken along line 6—6 of FIG. 5;

FIG. 7 is a partial sectional view taken along line 7—7 of FIG. 5;

FIG. 8 is a cross-sectional view of the present invention using areverse flow of clean water/salt water as part of theparticulate-removing means;

FIG. 9 is a partial sectional view taken along line 9—9 of FIG. 8;

FIG. 10 is similar to FIG. 9 except that a different reverse flowdirection is depicted;

FIG. 11 is an enlarged, cross-sectional view of a portion of FIG. 5,depicting different portions of the partition and one of the associatedwipers;

FIG. 12 is an enlarged, cross-sectional view of a portion of FIG. 5,depicting the passageways in the particulate-removing means support foruse with the alternative drain configuration;

FIG. 13 is a partial isometric view of the internal particulate chamberdepicting the partition and one of the wipers comprising the shoes;

FIG. 14 is a schematic of a water/salt water cleaning system using astationary water/salt water strainer;

FIG. 15 is a variation of the water/salt water cleaning system of FIG.14 wherein the downline water/salt water flow is used as the source ofthe reverse clean water/salt water flow;

FIG. 16 is another variation of the invention of FIG. 15;

FIG. 17 is a cross-sectional view of a stationary filter, that can beused in the systems shown in FIGS. 14-16, and having an ultrasonicgenerator disposed therein;

FIG. 18 is an enlarged view of the circled portion shown in FIG. 17; and

FIG. 19 is a sectional view of the stationary filter taken along line19—19 of FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the present invention. Thepresent invention has wide application where straining very smallparticulate contaminants, less than 100 microns and large percentage ofthese are less than 25 microns, from a water/salt water flow isrequired, and is not limited to the environment shown in FIG. 1, as willbe discussed in detail below. The present invention is characterized asa non-disposable cleaning device, i.e., having a porous member that canbe cleaned rather than being thrown away. The term non-disposable isdefined as an item that does not require periodic replacement, e.g.,once a day, week or month. Thus, such a non-disposable item has obviousadvantages in environments where storage is limited and cleaning devicereplenishment facilities are unavailable, e.g., ocean-going vessels.Other example systems include power plants, cogeneration facilities,etc.

As an exemplary environment, Applicants have depicted a waterdesalination system 1 for disclosing the preferred embodiment; such awater desalination system 1 may be used on watercraft, e.g., ships andboats. However, it should be understood that it is within the broadestscope of the present invention that it can be used in any water cleaningsystem and it is not limited to a water desalination system.

Referring now in greater detail to the various figures of the drawing,wherein like reference characters refer to like parts, there is shown inFIG. 1 at 520 a self-cleaning water filter of the present inventionwhich forms a part of the system 1. The water filter system 1 comprisesfive stages of straining/filtration followed by a reverse osmosis stage6. A pump 2 pumps sea water into a ⅛″ perforation self cleaning strainer3 which discharges to a cyclone separator 4 (also referred to in the artas a “centrifugal separator”), which discharges to a 50 micron selfcleaning wedge wire filter 5. The wedge wire filter 5 discharges to theself-cleaning wire cloth (e.g., 10-20 micron) water filter 520 which, inturn, discharges to a 3 micron cartridge filter 6 and finally throughthe reverse osmosis membrane 7 to a fresh water user/storage stage 8.

As shown more clearly in FIG. 2, the water filter 520 comprises twocanisters 26 and 28 that are fed the main water flow with particulates,e.g., the sea water, from the wedge wire filter 5 via a common inputmanifold 30 (e.g., 2½ inch class 150 ANSI flanged input) at the topportion of the filter 520. Each canister 26 and 28 has two inputs fromthe common manifold 30, as indicated by inputs 32A and 32B for canister26 and by inputs 34A and 34B for canister 28. Each canister 26 and 28comprises a cylindrical-shaped porous member 36 and 38, respectively,through which the sea water flows, as will be discussed in detail later.The porous members 36 and 38 comprise a screen selected from the groupconsisting of wedge wire, wire cloth and perforated metal. In thepreferred embodiment, the porous members 36 and 38 comprise wedge wirescreens, such as those manufactured by Leem Filtration Products, Inc. ofMahwah, N.J. It is also within the broadest scope of the presentinvention that the porous members 36 and 38 may comprise wire cloth orperforated metal, as opposed to wedge wire screens. One of the mainfeatures of the water filter 520 is its ability to filter out fineparticulate matter, e.g., particulates less than 100 microns, where alarge percentage of these are less than 25 microns.

Drive mechanisms 40 and 42 (FIG. 3) are provided to rotate therespective porous members 36 and 38 during the cleaning process abouttheir respective center axes, only one (44) of which is clearly shown inFIG. 5. Otherwise, during normal operation, the porous members 36 and 38remain stationary.

As can be seen in FIG. 2, sea water enters each canister through itsrespective inputs and then flows around the periphery of each porousmember 36 and 38; in particular, sea water flow from inputs 32A and 32Bare shown by arrows 46A and 46B, respectively, and sea water flow frominputs 34A and 34B are shown by arrows 48A and 48B, respectively. Theinputs 32A and 32B are located on both sides of an internal particulatechamber 50 (FIG. 7, which comprises two dislodge subchambers 50A/50B anda drain subchamber 50C, all of which are discussed later) in canister26; similarly, although not shown, the inputs 34A and 34B in canister 28are also located on both sides of a internal particulate chamber, alsocomprising two dislodge subchambers and a drain subchamber. Thus,water/salt water input flow moves away from the chamber 50 and aroundthe periphery of the porous members 36 and 38 and then through them, asis discussed next.

Sea water flow through the porous member is more easily depicted in FIG.5, which is a cross-sectional view of the canister 26, although itshould be understood that the following discussion is applicable to theother canister 28. The main sea water flow is through the porous member36, from an outside surface 37 to an inside surface 39, as indicated bythe arrows 52, and down through the hollow interior 41 of the porousmember 36. As the sea water then flows through the porous member 36,particulate contaminants are then trapped against the outer surface 37of the porous member 36. The filtered sea water exits into a main output54 of the canister, as shown by the arrow 56. FIG. 4 is a bottom view ofboth canisters 26 and 28 and it shows the main output 54 of canister 26and a main output 58 of canister 28 feeding into a common outputmanifold 60. Thus, sea water flow through the filter 520 is basicallycontinuous.

When cleaning of the porous member 36 and 38 is required, as indicatedby pressure drop across the filter 520 (as measured by a pressuretransducer, not shown), the drive mechanisms 40 and 42 are activated torotate the respective porous members. In addition, solenoid valves 72and 74 (FIG. 3) are activated to open respective drains (only one 76 ofwhich is shown in FIG. 5), located directly below the drain subchamber50C, for diverting the particulate debris and a limited amount sea waterdown through a respective drain, rather than through the main outlets 54and 58. Furthermore, it is within the broadest scope of this inventionto include other alternative locations for the drain, e.g., along thechamber, rather than under it, as will be discussed in detail later.Opening of the drain 76 (or the alternative drain) is kept to a minimumto discard as little sea water as possible while flushing theparticulate contaminants from the chamber. Thus, for example, the drain76 can be open all or any part of the time that the porous members 36and 38 are rotating.

Cleaning of the porous members 36 and 38 is accomplished by theparticulate-removing means, only one of which is shown most clearly inFIGS. 5, 7, 8 and 9; as such, the following discussion applies to theparticulate-removal means in the canister 28 also. In the preferredembodiment, the particulate-removing means comprises an elongated wirebrush 62 that spans the length of the porous member 36. The brush fibersare in contact with the outside surface 37 of the porous screen 36 andthus bear on the outside surface 37 of the porous member 36 along itsentire length. The brush 62 forms the separation between the twodislodge subchambers 50A and 50B, while the majority of a brush support63 is disposed inside the drain subchamber 50C, as shown in FIG. 7.

As mentioned previously, the chamber 50 comprises the two dislodgesubchambers 50A/50B and a drain subchamber 50C. The chamber 50 comprisesa pair of confining walls 64A and 64B, also running the length of theporous member 36, that enclose the brush 62/brush support 63. Thepurpose of these walls 64A and 64B is to contain the dislodgedparticulate debris within the chamber 50 so that substantially only seawater within this chamber 50 will be discharged through the drain 76 (oralternative drain 300, to be discussed later) during cleaning. Apartition 200, also running the length of the porous member 36, formsthe separation between the two dislodge subchambers 50A/50B and thedrain subchamber 50C. The partition 200 itself comprises a pair of outerflanges 202A/202B, a base wall 204 and sidewalls 206A/206B. The basewall 204 is secured between a particulate-removing means (e.g., brush 62or scraper) head 61 and the particulate-removing means support 63. Atthe bend between the sidewalls 206A/206B and the outer flanges202A/202B, the partition 200 comprises a plurality of apertures 212(FIGS. 7, 9, 11 and 12) that permit the passage of dislodged particulatecontaminants from the two dislodge subchambers 50A/50B to the drainsubchamber 50C. Because of the size of the apertures 212 (e.g., 0.094″diameter), once any particulate contaminants from the two dislodgesubchambers 50A/50B make their way through the partition 200, there isvery little chance that such particulate contaminants can find their wayback through the apertures 212 and ultimately return to the outersurface 37.

A drain passageway 75, through a strainer support housing 77, is alsoshown in FIG. 5. FIGS. 7 and 9 also show the passageway 75 in phantom.

At the extreme ends of the confining walls 64A and 64B, respectivewipers 65A and 65B are secured to the outside surfaces of the walls 64Aand 64B, respectively, and which also run the length of the porousmember 36. The wipers 65A and 65B (e.g., 316 stainless steel, half-hard)are coupled to the ends of the walls 64A and 64B using fasteners 78 andplates 79. As can be seen most clearly in FIG. 13, wiper 65A comprises aplurality of spaced-apart shoes or runners 67 that are in contact withthe outer surface 37 of the porous member 36. These shoes 67 (e.g.,0.010″-0.015″ thickness and ¼″ wide and which may be spot-welded to thewiper 65A) serve to maintain the wiper 65A a sufficient distance awayfrom the outer surface 37 such that during cleaning, while the porousmember 36 is rotating (direction of rotation is shown by the arrow 161in FIG. 7), the particulate contaminants adhering to the outer surface37 pass beneath the wiper 65A between the shoes and then are driven offof the outer surface 37 by the particulate-removing means 62 and intothe dislodge subchamber 50A. The drain subchamber 50C is in direct fluidcommunication with the drain 76 (or alternative drain 300). When thedrain 76 (or alternative drain 300) is open, any particulatecontaminants suspended in the dislodge subchamber 50A are pulled towardthe apertures 212 in the partition 200 and pass through them and out tothe drain 76 (or 300).

Any remaining particulate contaminants which cannot be mechanicallydriven off of the surface 37 by the brush 62, e.g., particulatecontaminants lodged in between the outer surface 37 and the insidesurface 39 of the porous member 36 (e.g., lodged in the wedge wire cellsof a porous member 36 comprising wedge wire), are subjected to a reversepressure and are driven out of the surface 37 into the second dislodgesubchamber 50B. In particular, unlike the first dislodge subchamber 50Awhich is not totally closed off since the wiper 65A stands off from theoutside surface 37 of the porous member 36, the second dislodgesubchamber 50B forms a completely-closed off chamber because the wiper65B does not include shoes and, therefore, is in contact with the outersurface 37 along its entire length. Thus, the second dislodge subchamber50B is subjected completely to the influence of the pressuredifferential created between the inside surface 39 of the porous member36 and the opened drain pressure which is present in the drainsubchamber 50C, via the apertures 212. When the drain 76 (or 300) isopen, these particulate contaminants, lodged in between the outersurface 37 and the inside surface 39 of the porous member 36, are drivenout of that region by the reverse pressure differential and then aresuspended in the second dislodge subchamber 50B; this pressuredifferential also pulls these particulate contaminants toward theapertures 212 in the partition 200 and into the drain subchamber 50C forpassage through the drain 76 (or 300).

As pointed out earlier, the particulate contaminants are of an extremelysmall size, less than 100 microns, and a large percentage of these areless than 25 microns; as a result, these particulate contaminants do notsettle out by gravity into the drain but rather, due to their smallsize, remain suspended in the sea water. The invention of the presentapplication is well suited to overcome this problem as described below.

It should be understood that the apertures 212 provide for fluidcommunication between the first dislodge subchamber 50A and the drainsubchamber 50C and for fluid communication between the second dislodgesubchamber 50B and the drain subchamber 50C. However, because theapertures 212 are small, they maintain a high velocity of particulatecontaminants from both the first and second dislodge subchambers 50A and50B into the drain subchamber 50C under the influence of the reversepressure differential. Such a high velocity cannot be sustained byreplacing the apertures 212 with a slot. Furthermore, replacing theapertures 212 with a slot would defeat the purpose of maintaining thetransferred particulate contaminants (i.e., particulate contaminantsthat have passed from the dislodge subchambers 50A/50B) in the drainchamber 50B since the particulate contaminants would not be precludedfrom making their way back to the outer surface 37 of the porous member36.

In particular, the advantage of using the plurality of apertures, asopposed to a slot of the type shown in U.S. Pat. No. 5,595,655 (Steineret al.), is that the plurality of apertures provides for a rapid flowvelocity as opposed to a low flow velocity for the slot. For example, ifthere are 21 apertures that form one set of apertures in the partition200, each having a diameter of approximately 0.094″, then the total areais approximately π(0.094″/2)²×21=0.1457 in². If, on the other hand, aslot having a width of 0.094″ and a length of 12.594″ (i.e., the lengthfrom the top of the uppermost aperture in the partition 200 to thebottom-most aperture in the partition 200; this is a reasonableassumption since the Steiner et al. patent states that the slot issubstantially equal to the scraper length-Steiner et al. patent, col. 1,lines 61-62) is used, the area is 1.184 in². Thus, using a plurality ofapertures presents only ⅛ the area of the slot. As a result, for a givenflow rate (gallons/minute), the slot may provide flow velocity of 1ft/sec whereas the apertured partition generates a flow velocity of 8ft/sec. The higher velocity significantly reduces the chance that aparticulate will migrate backwards through the plurality of aperturesand reattach to the porous surface 36.

It is also within the broadest scope of the present invention to includean alternative drain 300 configuration as shown most clearly in FIGS. 5,8 and 12. To that end, a drain 300 is depicted along side the drainsubchamber 50C rather than disposed underneath the subchamber 50C, asdiscussed, previously. The drain 300 comprises drain passageways 302,304 and 306 that form a portion of the particulate-removing meanssupport 63. The passageways 302-306 are coupled at one end to a commonmanifold 308 through which the dislodged particulate contaminants aredisposed of. As shown in FIG. 12, the other end of each passageway302-306 comprises a respective cross hole 310, 312, and 314 disposed inthe drain subchamber 50B. Thus, when a drain solenoid valve 316 (FIG. 5)is activated as discussed previously, particulate matter that has beendislodged from the outer surface 37 of the porous members 36/38 into thetwo dislodge subchambers 50A/50B, passes through the apertures 212 inthe partition 200 into the drain chamber 50B. From there, the dislodgedparticulate contaminants are driven into the cross holes 310-314,through the passageways 302-306 and then into the common manifold 308.Thus, particulate contaminants dislodged from the outer surface 37 ofthe porous members 36/38 would be driven into the alternative drain 300.

Alternatively, instead of using a single solenoid valve 316, it iswithin the broadest scope of this invention to include dedicatedsolenoid valves 318, 320 and 322 (FIG. 5) that individually couplerespective passageways 302-306 to the common manifold 308.

It is also within the broadest scope of the present invention that theterm particulate-removing means include a brush, a scraper, or anyequivalent device that is used to dislodge particulate contaminants fromthe outside surface 37 of the porous members 36 and 38. For example,where larger particulate contaminants are to be filtered from the waterflow, a scraper (not shown) can be used in place of the brush 62.

It is also within the broadest scope of the present invention that theparticulate-removing means also encompasses a reverse flow of cleanwater for dislodging the particulate contaminants from the water filter520; or a reverse flow of clean water in combination with theparticulate-removing member (e.g., brush or scraper), discussedpreviously.

In particular, as shown in FIGS. 8-10, a second embodiment of thepresent invention comprises a particulate-removing means that includesan elongated spraying element 151 comprising a plurality of ports 153.The elongated spraying element 151 is coupled to a pressure source 155(e.g., a pump, air supply, etc.) that recirculates clean water (whoseflow is indicated by the arrow 56) into the elongated spraying element151, during cleaning only, to create a high energy water spray thatemanates from each of the ports 153. As shown most clearly in FIG. 9,the direction of the high energy spray (indicated by the arrow 157) isfrom the inside surface 39 to the outside surface 37 of the porousmember 136. Thus, as the porous member 36 is rotated (directionindicated by the arrow 161) during cleaning, the high energy spraydrives the particulate contaminants from the outside surface 39 into thedislodge subchamber 50B.

It should be understood that the particulate-removing means may comprisethe elongated spraying element 151 alone for driving off the particulatecontaminants, or the particulate-removing means may comprise aparticulate-removing member (e.g., a brush 62 or scraper) in addition tothe elongated spraying element 151, as shown in FIGS. 8-9. Together, theelongated spraying element 151 and the particulate-removing member(e.g., brush 62 or scraper) act to dislodge the particulate contaminantsfrom the outside surface 37 of the porous member 36 during cleaning.When the particulate-removing member (e.g., a brush 62 or scraper) isused in combination with the elongated spraying element 151, thedirection of the high energy spray (indicated by the arrow 163) may beset to occur after the particulate-removing member dislodges some of theparticulate contaminants (FIG. 10), thereby driving particulatecontaminants into the second dislodge subchamber 50B.

The porous member 36, for use in this second embodiment, comprises anopen lower end 137 (FIG. 8) to permit passage of the elongated sprayingelement 151 therethrough.

Another variation of the self-cleaning water filter that utilizes areverse flow of clean water for cleaning purposes is depicted at 220 inFIG. 14. In particular, as indicated by the arrow 165, during normaloperation, sea water enters through an inlet valve 167 to a water filter220. During normal operation, a drain valve 171 and a purge valve 173remain closed, as will be discussed in detail later. The water filter220 comprises a porous member 236, preferably having a wire clothconfiguration. The direction of the main sea water flow through theporous member 236 is given by the arrows 52 and is similar to the flowfor the porous members discussed previously, i.e., from an outsidesurface 37 of the porous member 236 to an inside surface (not shown) ofthe porous member 236 and then through the center portion 41 of theporous member 236. The cleaned sea water is then passed through anoutlet valve 175 in the direction of the arrow 177.

The cleaning process for the water filter 220 is different from theprevious embodiments in that the porous member 236 does not move duringcleaning. Instead, a reverse flow of clean water (the direction of thisreverse flow is given by the arrow 179) is injected down through thecenter of the porous member 236, from the inside surface to the outsidesurface 37 of the porous member 236. This reverse flow of clean waterimpacts the entire inside surface of the porous member 236 and flows tothe outside surface 37 of the porous member 236, thereby dislodging theparticulate contaminants from the outside surface 37 of the porousmember 236. Since this reverse flow acts through the entire porousmember 236, there are no confining walls used. Thus, in this embodiment,the particulate removal means comprises only the reverse flow of cleanwater. Because this reverse flow of clean water is applied through theentire porous member 236, the water filter 220 must be isolated from thenormal sea water flow during cleaning, as will be discussed in detailbelow.

In particular, when cleaning is required, the inlet valve 167 and outletvalve 175 are closed and the purge valve 173 and drain valve 171 areopened. The purge valve 173 is coupled to a clean water reservoir 181which is under pressure (e.g., an air supply, whose input flow isindicated by the arrow 183 and having a valve 185 for maintaining airpressure in the reservoir 181. The downstream clean water, indicated bythe arrow 187, enters the reservoir 181 through a recharge valve 189).When the purge valve 173 and the drain valve are opened, the reverseflow of clean water 179 drives the particulate contaminants off of theoutside surface 37 of the porous member 236; this reverse flow, nowcontaining the dislodged particulate contaminants, flows out, asindicated by the arrow 191, through the drain valve 171. Once this flowof dislodged particulate contaminants passes to the drain, the purgevalve 173 and the drain valve 171 are closed and the input valve 167 andthe output valve 175 are opened, restoring normal sea water flow.

It should be understood that the continuous sea water flow isaccomplished by having a plurality (e.g., five to eight) parallel,non-rotating filter paths (not shown) that are coupled to the reservoir181 through respective purge valves 173. Thus, when any one non-rotationfilter path is being cleaned using the reverse water flow, the remainingparallel channels are operating under the normal sea water flow.

Another variation of this embodiment, depicted in FIG. 15, uses thedownstream clean water directly to create the reverse water flow. Inparticular, the purge valve 173 is coupled directly to the downstreamclean water flow. The sequence of valve openings/closings are similar tothat described previously. Thus, when the purge valve 173 and the drainvalve 171 are opened a pressure differential is created and the reverseflow of clean water, the direction indicated by the arrow 179, isgenerated directly from the downstream clean water flow.

Another variation of this embodiment is shown in FIG. 16 that usespassive components such as a check valve 400 and a flow restrictingorifice 402 in place of the purge valve 173.

It should also be understood that the variations of FIGS. 15 and 16,like that discussed with regard to FIG. 14, also comprise a plurality ofparallel, non-rotating filter paths that permit the continuous flow ofsea water when any one of the parallel, non-rotating filter paths isbeing cleaned by the reverse flow of clean water.

FIGS. 17-19 depict an exemplary stationary filter 220′, having anultrasonic generator 300 disposed therein, that can be used in thesystems shown in FIGS. 14-16 and, more preferably, to the systems ofFIGS. 15-16.

Before proceeding with a discussion of FIGS. 17-19, it should beunderstood that in FIGS. 14-16, the input flow 165 is shown in an upwarddirection from the bottom of the page toward the outlet flow 177 shownat the top of the page, for clarity only. The actual flow of any of thesystems shown in FIGS. 14-16 is exemplary only and may be in any numberof directions and, therefore, is not limited to those depicted in thosefigures. Thus, the orientation of the stationary filter 220′ shown inFIGS. 17-19 is simply inverted from that shown in FIGS. 14-16. Thus, the“top surface” 221′ in FIG. 17 corresponds to the “bottom” surface 221shown in FIGS. 14-16.

As will also be discussed in detail later, the input line into thestationary filter 220′ is from the side of the canister 26′, at an inputport 32′, rather than from the “bottom” surface 221 shown in FIGS.14-16; the reason for this will also be discussed later. In addition, adedicated drain port 376 passes the dislodged particulate contaminantsaway from the stationary filter 220′ to a drain (not shown). Because ofthese port configurations, the input tee 291 in the systems of FIGS.14-16 is eliminated.

As shown in FIG. 17, the stationary filter 220′ is housed in thecanister 26′. On one side of the canister 26′ is the input port 32′while on the other side of the canister 26′ is the drain port 376; atthe bottom of the canister 26′ is an output port 54′. The ultrasonicgenerator 300 is disposed inside the hollow interior 41 of thestationary filter 220′. The inlet valve 167 is coupled to the port 32′and the drain valve 171′ is coupled to the drain port 376. The valves167/171′ and the ultrasonic generator 300 are operated by a controller(not shown) during the cleaning process of the stationary filter 220′itself, as will be discussed later.

As shown most clearly in FIG. 19, the stationary filter 220′ ispositioned inside a chamber formed by a circular wall 380. The wall 380comprises a plurality of sets (e.g., eight) of vertically-aligned holes(e.g., ¼″ diameter) dispersed around the circular wall 380 (see FIG.17); one hole 382 of each of the plurality of vertically-aligned holesis shown in FIG. 19. As will be discussed in detail later, the circularwall 380 acts to minimize the effects of the high velocityparticulate-contaminated input flow 165, as well as to deflect anddisperse the flow 165 all around the stationary filter 220′.

The stationary filter 220′ comprises three parts: (1) an outer wirecloth layer 384 (e.g., 5 microns); (2) an inner 40-50 mesh layer 386;and (3) an inner perforated metal enclosure 388 (e.g., 16-18 gauge,stainless steel) all of which are microwelded together. The perforatedmetal enclosure 388 comprises staggered holes 390 (e.g., ¼ diameter, seeFIG. 17) that results in an overall surface area that is approximately50-60% open. The outer wire cloth layer 384 filters out the particulatecontaminants of incoming water/salt water flow that passes through theholes 382 in the circular wall 380; in particular, as the incomingwater/salt water flow 165 passes through an outer surface 385′ (see FIG.18) of the wire cloth layer 384 to an inner surface 385″ of the wirecloth layer 384, the particulate contaminants lodge against the outersurface 385′. The 40-50 mesh layer 386 disperses the cleaned input flowaround the periphery of the perforated metal enclosure 388 and throughall of the holes 390 therein. The cleaned water/salt water flow thenflows downward through the hollow interior 41 of the stationary filter220′ and through the output port 54′.

Although not shown, another version of the stationary filter 220′comprises only two parts: (1) an outer wire cloth layer (e.g., 5-20microns) directly over a wedge wire inner layer with {fraction (5/16)}inch slot openings between the turns of wedge wire. Advantages of thissecond version of the stationary filter 220′ are that it allows a 90%open area as well as more direct contact with the backwash flow and theultrasonic waves.

As can also be seen most clearly in FIG. 19, several continuous supportmembers 392 are disposed between the outer wire cloth layer 384 of thestationary filter 220′ and the circular wall 380. These continuoussupport members 392 form independent sectors 394 (e.g., eight, FIG. 19)around the periphery of the wire cloth layer 384. As mentioned earlier,during normal sea water flow, the effects of the high velocityparticulate-contaminated input flow 165 are minimized by the presence ofthe circular wall 380 and the sectorization formed by the continuoussupport members 394; these sectors 394 segment the input flow 165 sothat the input flow 165 impacts the wire cloth layer 384 around theentire stationary filter 220′. In particular, once theparticulate-contaminated input flow 165 in each sector 394 passesthrough the vertically-aligned apertures 382, the input flow 165encounters the outer surface 385′ of the wire cloth layer 384 whichtraps the particulate contaminants therein. As also mentioned earlier,the cleaned water then passes through the 40-50 mesh layer 386 whichdisperses the cleaned input flow around the periphery of the perforatedmetal enclosure 388 and through all of the holes 390 therein. Thecleaned water flow then flows downward through the hollow interior 41 ofthe stationary filter 220′ and through the output port 54′

The stationary filter 220′ is releasably secured inside the canister 26′using four tie bars 396 (FIG. 19) that couple between a lower baseplate398 and an upper securement surface 400. To properly seal the stationaryfilter 220′ inside the canister 26′ an upper annular seal 402 (e.g.,rubber, see FIG. 18) and a lower annular seal 404 (e.g., rubber) areused.

The ultrasonic generator 300 (e.g., the Tube Resonator RS-36-30-X, 35kHz manufactured by Telsonic USA of Bridegport, N.J.) is releasablymounted in the hollow interior 41 of the stationary filter 220′. Inparticular, an elongated housing 393 of the ultrasonic generator 300 issuspended in the hollow interior 41 of the stationary filter 220′. Thus,when the reverse flow of clean water/salt water 179 occupies the hollowinterior 41, the ultrasonic generator 300 is energized wherein theultrasonic energy is applied to the wire cloth layer 384 in thedirection shown by the arrows 395 through the holes 390. The elongatedhousing 393 is attached to an electrical connector 397 which forms theupper portion of the ultrasonic generator 300. The electrical connector397 is then releasably secured to the canister 26′ (e.g., a nut 399). Awire harness 401 provides the electrical connection to the ultrasonicgenerator 300 from the controller (not shown). In this configuration, itcan be appreciated by one skilled in the art, that the ultrasonicgenerator 300 and stationary filter 220′ can be installed/replacedrather easily without the need to disconnect any plumbing from the inputport 32′, output port 54′ or drain port 376.

During normal operation, the inlet valve 167 is open and the drain valve171′ is closed, thereby allowing the contaminated water/salt water flow165 to be cleaned by the stationary filter 220′ as discussed above. Whenthe stationary filter 220′ itself is to be cleaned, the controller (notshown) closes the inlet valve 167 while opening the drain valve 171′. Asa result, a high pressure reverse flow 179 of clean water flows from theoutput port 54′ and through the three-part stationary filter 220′ andout through the drain port 376. As this reverse flow 179 passes throughthe wire cloth layer 384, the particulate contaminants are dislodgedfrom the outer surface 385″ of the wire cloth layer 384 and then drivenout through the drain port 376. It should be noted that during this highpressure reverse flow 179, the continuous support members 392 also actto prevent the wire cloth layer 384 from separating from under layingsupport. The reverse flow 179 is applied for a short duration (e.g.,approximately 4-5 seconds).

At the end of this application, and while there is still clean water inthe hollow interior 41 but where the flow 179 is simply migrating (e.g.,movement of clean water in inches/minute) rather than flowing, thecontroller (not shown) activates the ultrasonic generator 300 for alonger duration (e.g., 30 seconds to a couple of minutes) to provide forfurther cleaning of the wire cloth layer 384 by using ultrasonic energyto dislodge any remaining particulate contaminants in the wire clothlayer 384 into the migrating water flow and out through the drain port376.

Without further elaboration, the foregoing will so fully illustrate ourinvention and others may, by applying current or future knowledge,readily adapt the same for use under various conditions of service.

We claim:
 1. A method for removing particulates from a stainerpositioned in a contaminated water flow having particulates therein,said method comprising the steps of: disposing a first outer surface ofa stationary cylindrical porous member in the contaminated water flow tocapture particulates against said first outer surface; positioning aportion of a housing containing an ultrasonic energy source within aninner region of said stationary cylindrical porous member defined by adownstream second inner surface of said stationary cylindrical porousmember, said second inner surface permitting passage of a cleaned waterflow; isolating said stationary cylindrical porous member from saidcontaminated water flow, activating said ultrasonic energy source todislodge particulates from said first outer surface; and sending areverse flow of clean water through said second inner and first outersurfaces to evacuate said dislodged particulates from returning to saidfirst outer surface.
 2. The method of claim 1 wherein said step ofsending a reverse flow of clean water comprises sending a reverse flowof said contaminated water flow that has already passed through saidsecond inner surface.
 3. A method for reducing the amount of cleanedwater required in cleaning a particulate strainer using a reverse flowsystem, said method comprising the steps of: disposing the a stationarycylindrical strainer in a first fluid flow to capture particulatesagainst a first upstream surface of the strainer, positioning a portionof a housing containing an ultrasonic energy source within an innerregion of said stationary cylindrical strainer defined by a down streamsecond surface , said second surface permitting passage of a cleanedfluid flow; stopping said first fluid flow; activating said ultrasonicenergy source to dislodge particulates from said first surface; sendinga reverse flow of said cleaned fluid flow through said second surfaceand through said first surface to evacuate said dislodged particulatesfrom returning to said first surface; and restoring the passage of saidfirst fluid flow through said strainer.